水-热耦合作用下压实黏性土干缩裂隙发育过程及理论模型研究

工程中的压实黏性土在气候作用下很容易发生干缩开裂现象，导致土体工程性质显著弱化，并诱发各种工程地质问题和环境地质问题。本项目以压实黏性土作为研究对象，分别开展室内试验和原位试验，重点考虑气候作用下的水-热耦合因素，围绕干缩裂隙发育过程及理论模型这一中心课题，针对压实黏性土的蒸发失水特性、体积变形响应、裂隙演化规律及张拉破坏行为开展系统研究，结合微观结构分析，阐明压实黏性土在水-热耦合条件下的蒸发-收缩-开裂互馈过程及机理。在此基础上，进一步探讨压实黏性土持水特性的温度效应，并结合非饱和土力学理论和概率理论，构建考虑水-热耦合效应和土体微观结构影响的干缩开裂本构模型和裂隙网络几何形态预测模型，以期使本项目研究成果为工程地质抗旱减灾提供指导。

In engineering practice, desiccation cracking always develops in compacted clayey soils under atmospheric environment. Cracks may have a negative influence on soil properties and then cause a series of engineering geology and environmental geology problems. In this project, a compacted clayey soil is selected as the typical test material. In order to understand coupled effects of relative humidity and temperature on desiccation cracking, both the laboratory test and the in-situ test will be conducted. The following subjects will be systematically investigated: evaporation, volumetric behavior, desiccation cracking and tensile failure. With combination of microstructural analysis, the evaporation-shrinkage-cracking interaction mechanism under hydro-thermal loading will be revealed. On this basis, thermal effects on water retention characteristic of the clayey soil will be further investigated. Moreover, with combination of unsaturated soil mechanics and theory of probability, a new cracking constitutive model and a prediction model of geometric characteristics of cracks considering the effects of hydro-thermal loading and soil microstructure will be proposed. The achievement of this project will provide scientific guidance for directing drought resisting and disaster reduction in engineering geology field.